The Master poses as the new vicar in the rural community of Devil's End,
just as an archaeologist begins work on opening an ancient barrow near the
village. Despite the Doctor's attempts to stop the work, a Daemon named
Azal is released from dormancy within the barrow. A member of an ancient
alien race who guided nascent human life on Earth, Azal has remained
behind to judge humanity's worthiness. But the Master will stop at nothing
to seize Azal's tremendous power.

Production

Doctor Who producer Barry Letts had an abiding interest in black
magic, dating back to his youth when he read Dennis Wheatley's 1935 novel
The Devil Rides Out. In June 1970, when he had to compose an
audition piece for the roles of Jo Grant and Mike Yates, Letts drew on
this fascination, devising a scene in which Jo and Mike are confronted by
the Devil in a church.

Some time thereafter, Letts decided that he should try his hand at writing
a Doctor Who adventure himself to see what it would be like to work
under his own restrictions. Letts had some writing experience already,
including some Doctor Who storylines which had been rejected by
then-story editor Gerry Davis in late 1966. Although Letts wanted to
incorporate his interest in the occult into his scripts, he was initially
reluctant, fearing that this would run contrary to Doctor Who's
traditionally rational standpoint. However, script editor Terrance Dicks
encouraged Letts to expand upon his audition piece, observing that an
element of his story could be the explanation of magic in scientific
terms.

Terrance Dicks encouraged Barry Letts to expand his
audition script into a full story

Letts ultimately agreed, but decided that he should recruit a more
experienced cowriter to join him on the project, which would serve as a
back-up final serial in case of scripting problems on Doctor Who's
eighth season. He was able to secure the involvement of Robert Sloman, a
former actor in repertory theatre who had written for stage and radio. The
duo found further inspiration in the 1969 work Chariots Of The Gods
by Erich von Daniken, a text which proposed that aliens had visited Earth
before the rise of man. This led to the notion of the devil-like alien
(which was first called a Damon, then a Demon) dwelling within a burial
mound.

The storyline for “The Demons” was commissioned from Sloman on
December 17th, followed by the scripts three weeks later, on January 6th,
1971. It was agreed that the serial would be credited to the pseudonym
“Guy Leopold” (the first name being that of Sloman's son, and
the surname being Letts' middle name). This was done in part to avert
concerns by the Writer's Guild about a producer writing for his own show,
and also because Sloman wanted to avoid the appearance of the dissolution
of a writing partnership in which he was then involved. Like all the
Season Eight stories, “The Demons” featured the Master, but by
now Letts was aware that having the character appear in all the year's
serials was a mistake. As a result, it was agreed that the adventure would
culminate in his arrest by UNIT.

Letts and Sloman had to tread carefully with the way they handled
religious elements in “The Demons”. This resulted, for
instance, in the relocation of the Master's coven's rituals from the
church itself to the crypt -- referred to exclusively as the
“cavern” -- underneath. Similarly, a reference to the Devil as
“the Horned God” was changed to “the Horned
Beast”. Particularly contentious was the incantation chanted by the
Master at his black sabbath; ideas such as having him intone the Lord's
Prayer or Eskimo Nell backward were considered before Letts finally
decided upon a reverse recitation of Mary Had A Little Lamb.

Letts also hoped to expose more of the private lives of the UNIT team in
“The Demons” (hence Yates and Benton appearing out of
uniform), and to this end Dicks suggested including the Brigadier's wife,
whom he proposed might be called Fiona. Nicholas Courtney was not in
favour of this, however, and it was not included in the scripts. One jokey
element which Letts did insert was the scene where Jo gets the Doctor lost
because she's been holding a road map upside-down. This was inspired by a
real incident when Jon Pertwee and Katy Manning were driving to a location
shoot.

The scene where Jo gets the Doctor lost was inspired by a
real incident involving Jon Pertwee and Katy Manning

By early 1971, it was clear that “The Demons” would indeed
have to be pressed into service as the fifth adventure of Season Eight,
earning it the production code Serial JJJ. Letts originally hoped to
direct the story himself, but ultimately secured the services of
Christopher Barry, who had not worked on Doctor Who since The Power Of The Daleks almost five years
earlier. It was Barry who asked that the serial be retitled The
Daemons, as he felt that the archaic spelling lent the serial
additional atmosphere.

The Daemons was allocated more location work than usual, spanning
twelve days from April 19th to 30th; filming was interrupted only on the
intervening Sunday, the 25th. All the locales used were in Wiltshire, with
the town of Aldbourne being the site of the majority of the work. The
19th, however, saw scenes filmed in Membury -- the UNIT garage and the
crossroads -- and in Knighton, for further roadside scenes. The only other
non-Aldbourne location was Darrell's Farm in Ramsbury, for the scenes at
the edge of the heat barrier. Filming there took place on the 23rd, 26th
and 27th. The remaining days were all spent within the confines of
Aldbourne, particularly on the grounds of the Church of St Michael and
in the vicinity of the Blue Boar, the local pub which was renamed the
Cloven Hoof for the duration of filming. Many Aldbourne residents
participated in the recording, and the two week period would subsequently
be generally acknowledged as a high point of the entire Pertwee era.

Because so much material had been captured on film, The Daemons
required only three studio days; the normal Doctor Who formula was
to have one such day per installment. As a result, the
two-episodes-per-fortnight recording pattern was disrupted for this
serial. Instead, the first day of taping came on Tuesday, May 11th, in BBC
Television Centre Studio 4. All the remaining material for part one was
captured, alongside all the part two scenes except those set in the
bedroom at the Cloven Hoof and the vicarage, and the Doctor's encounter
with Bok. Courtney was pressed into additional service as the voice of the
BBC3 announcer.

Nicholas Courtney was pressed into additional service as
the voice of the BBC3 announcer

Recording resumed on Wednesday, May 19th, again in TC4. Parts two and
three were completed, and some episode four material was also enacted,
including the scenes in the bedroom, the vicarage and the UNIT mobile HQ,
plus the scene where Benton and Miss Hawthorne hear the arrival of the
Morris Dancers. It was Christopher Barry's turn to provide a vocal
performance on this day, as he played the RAF pilot.

Work on The Daemons -- and Doctor Who's eighth production
block as a whole -- then concluded a week later, on May 26th. The venue
this time shifted to TC3. The day saw the recording of the outstanding
sequences from part four and all the studiobound scenes for episode five.
The broadcast of this installment on June 19th brought Season Eight to a
close.

Sources

Doctor Who: The Handbook: The Third Doctor by David J Howe and
Stephen James Walker (1996), Virgin Publishing, ISBN 0 426 20486 7.